Bøker av Shinsuke Tamura

Although e-cash systems are widely used, currently available e-cash is not a complete replacement of real cash, e.g. authorities can know merchandise for which the e-cash was paid from information included in e-cash despite they may be secrets of the cash holders. Also, protection of e-cash from dishonest entities in offline environments is not easy. A payee of e-cash cannot determine whether the e-cash a payer is paying was used already at other places or not when databases about already used e-cash are not available for example. To completely replace real cash with e-cash, this book develops a self-issuable e-cash scheme that satisfies all essential requirements. Namely, cash holders cannot forge e-cash and only a legitimate cash holder can use its e-cash. Also, no one except cash holders themselves can know their purchases or can link their consecutive purchases. In addition, cash holders can divide their e-cash into ones of arbitrary values to pay for small purchases, they can use e-cash that was paid by others, and e-cash is protected from dishonest uses even in offline environments where databases about issued or used e-cash are not available.

Outlines the benefits and drawbacks of anonymous security technologies designed to obscure the identities of users. These technologies may help solve various privacy issues and encourage more people to make full use of information and communication technologies, and may help to establish more secure, convenient, efficient, and environmentally-friendly societies.